


Demonatomy 101

by skyeofdragons



Category: Gravity Falls
Genre: (it's REALLY mild), Aftercare, Chubby Dipper Pines, Come Inflation, Come Swallowing, Consensual, Crossdressing, Doggy Style, Established Relationship, Frottage, Gentle Sex, Lingerie, M/M, Monster Bill Cipher, Multiple Arms, Multisex Bill Cipher, Neon Genitals, Non-Human Genitalia, Not Quite PWP But Pretty Close, Older Dipper Pines, Oral Sex, Other, Reverse cowgirl position, Sex, Size Difference, Tentacle Dick, Tentacle Sex, Tentacles, Thigh sex, Vaginal Fingering, Vaginal Sex, Weird Biology, Weird Semen
Language: English
Status: In-Progress
Published: 2016-10-30
Updated: 2017-08-01
Packaged: 2018-08-27 20:42:18
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 7,830
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8416078
Author URL: https://archiveofourown.org/users/skyeofdragons/pseuds/skyeofdragons
Summary: Bill's got one of his monstrous forms back, and Dipper becomes curious about what demon dick is like. Not quite PWP, but the plot is porn.





	1. Demon Dick

**Author's Note:**

> Bill's got three sexes: Male, Female, and Other. If you are not comfortable with the Female or Other portions, do not read anything but the first chapter.

Dipper sighed as Bill curled around him for the millionth time that day, as was the tendency every time he stopped to sit down outside. That’s where Bill had to be, by sheer necessity, until he regained enough control over his magic to shift into a smaller form. It might be nice to have a demon boyfriend, but it wasn’t so great when he stretched across two rooms of the Shack, with his tail-puppet self papping gently at the register and fucking up the totals for the day. This time, Bill had chosen to only curl his front torso behind his mate, while his secondary chest and hind-area coiled up the nearest tree, forty feet of interdimensional mass and oddity making the higher limbs bow under the weight of one of his hindlegs. The head large as his own torso was gentle as he leaned into the human, and the human rested on a soft, flat cheek.

Laying back like this, his head resting on Bill’s, he had a nice view of the thing that had so frankly claimed him, and a vague curiosity overtook him as he looked up the winding, feline-in-flexibility body that draped itself over a bough no less than twenty feet off the ground like some kind of abandoned Mardi Gras feather boa.

“So, uh… Bill… When you were human…” He began, turning his head to meet the nearest of the smaller, unblinking obsidian eyes that stared at everything. He could never tell what Bill was looking at, since they might as well have been ink drops on his face, but he knew Bill was listening by how one tufted ear swiveled towards him. “When you were human, you and I… Well. I mean you had a- You know- Bits. Like a person.”

 

“I should hope you remember that,” came the purred response, deep and soft, like a boat’s propeller under the water, rumbling and pulsing with impressive engines behind it. “You only enjoyed it nearly nightly for a while.”

 

His words brought Dipper to smack the nearest knuckle on his long-fingered hand, like a hamsa in shape, with the three true fingers centered, a thumb on either side. A deep crackling sound, boulders crashing down a mountainside, showed Bill had found his small reprimand amusing.

 

“I assume you are wondering where such things went,” the demon said, then, largest eyes of the eight blinking, long lashes swiping down Dipper’s arm, oversized brush bristles. Dipper rubbed his arm, dulling the strange feeling, and nodded. Bill saw him. Bill could see so much.

 

Like a liquid, or a ferret, Bill slid his way down the tree, unlooping himself with grace no snake could mimic, creeping on his belly until Dipper was surrounded in coils of flesh, the air warmed by the demon’s own body heat. It made Dipper shiver, and curl back into the warmth out of habit, body momentarily hoping to receive those dextrous tongues again, before his brain snapped the littler head out of such imaginings. He was faced with the space between Bill’s hindlegs, and one of the parrotlike feet reached and grabbed his slightly-plush form and pulled him in closer, gentle enough to not hurt him, setting him on a muscled and heated thigh. The other leg stayed raised, four opposing toes lazily still and warm in the sun.

 

“Look,” said Bill, and Dipper did, staring at the carp-belly white skin, looking for something off, whatever Bill might be talking about. All he saw were blue veins under the surface, laced in strange patterns, bodily systems Dipper could not imagine the workings of.

 

“It’s… There’s nothing there,” he ventured, blushing as he poked at the smooth, warm skin, the lack of anything obvious confusing him, and perhaps making him a little sad. How did Bill expect to…? No, nevermind. If Bill and he would do anything like that, Bill had a mouth and crazy tongues; it would work just fine.

 

“Go ahead and pet me, then,” the demon chuckled, and this time it was cars rumbling to life, thousands at a time.

 

He listened, and pushed his small, small hand over Bill’s body, stopping slightly below an oddly coiled muscle ring- must be his own hole, Dipper realized, given its positioning beneath the prehensile tail- But he’d never really ventured here too frequently, given Bill was usually busy elsewhere, talking or snuggling. Was this what he was meant to see?

 

His hand pulled away, then, as he let out a soft little “Ah?-” of surprise, as the skin began to grow plump and soft, heating up further. He looked to Bill, resting his head on his own body lazily, and saw blue rising to the area under his jaw- how he blushed, Dipper knew, after enough instances of that happening. So he was doing something right. He focused his efforts on the flushed area, noticing something like scales forming some kind of arrow point, before a strange scent hit him: Cinnamon, or maybe cloves. No, definitely cloves. He checked again with Bill, and the demon blinked slowly once, a signal he wasn’t fucking up, at least. Now, when he looked, there were lines of a deeper cobalt, not the soft periwinkle his blood seemed to be, and, touching one, he found it soft, and balmy, and wet. He made a soft “Ghh!” as he pulled his hand away in shock and the confused sort of disgust one has when you aren’t sure what it was a hand has come in contact with, and shook away the heady scent of cloves that was making his nose and lips tingle and eyes water. “Bill! You- Is that a- A girl thing-”

 

Bill smiled, thin lips turning to lines revealing snaggle-teeth. “Yes and no. Are you going to stop?”

 

Dipper puffed his cheeks out in a pout and went back to touching.

 

Under clumsy hands, the lines widened into a Y, with the tail of the Y ending shortly before the end of what would probably be assumed a pelvis. Tracing his fingers along the separation in perfect skin, he found it to be natural, or at least not bleeding. It was weird, sure, but then again he was also dealing with a demon that seemed to be a dinosaur chameleon ant spider thing, so maybe internal genitalia weren’t the strangest thing he’d ever see. Bill was clenching his raised foot, now, and curling it closer to his body, trying to give room for something. His motions caused what seemed to be muscle flaps to uncurl, flattening open against his belly, covered in hundreds of bumps like tongues and their tastebuds. Dipper took a moment to run his hands over the cobalt surface, and was met with exactly that, what felt like tongue-tips rubbing his fingers and palms. He was oily and clove-scented when he pulled back, and looked up at Bill, who shifted himself slightly and put his ears back.

 

“Are you still comfortable with this?” The demon asked his little dear, and Dipper nodded quickly, giving himself a bit of whiplash. He could only imagine how good it would feel to rub on one of those, feel it over his plump thighs and ass and… He realized warmth was pooling too quickly in his belly, and coughed. Must be the cloves’ scent getting to him, making him feel warm and tingly. This was meant to be informative, he hadn’t implied anything about… That... He saw an odd series of bumps, two tubes, it looked like, curled inside, and touched the one that appealed the most to him. Tapered, and a green-and-pink gradient at that point, he rubbed the slowly shifting colour and his eyes widened. A soft sucking sound, foreign and familiar, something being drawn out of a wet hole. His jaw dropped as something longer than his leg pulled itself out of Bill, and stayed there, half-curled in midair, slick and shining with bodily fluids, some kind of internal lubricant that must be the source of the cloves-scent. Bill’s largest eyes shut and he let out a breath, like some great, relieved sigh, before opening them again and turning himself to view Dipper’s actions fully, giving him primary attention.

 

Dipper didn’t have sense enough to shut his mouth as he reached to touch what had to be the biggest cock in Gravity Falls (and of course it belonged to the biggest dick, too); a vibrant lime at the tip; he wanted to lick it and see if it tasted like a key lime pie, it looked so appealing in its rounded, dripping glory. It laid across his lap as he eased it closer to look, and while it didn’t quite pulse from heartbeat, it wasn’t still. The tip tended to flick towards his hands, and as a whole it pressed into his soft belly, teasing its way under his shirt. Bill hasn’t had this out with me, he thought to himself, and wondered just how pent-up his demon boyfriend had to be, after weeks spent pleasuring him- he’d been so selfish, not doing anything back.... He bit his lip and tried to figure out what exactly to do, however, with a four-foot dick and a five-and-a-half-foot body, given that it’d probably be a bit of a dick move to just say he was done now. So, he started by seeing just where it seemed to end, finding the base to be carnation pink, right at the front of the Y, indeed as if someone had overturned a flower and stem onto his body and then made the colours neon. Bill let out a purr as Dipper’s hands ran over him, and the vibrations went all the way throughout his body and into Dipper’s.

 

The human grew hard immediately, from the scent, from the clear pleasuring Bill was experiencing, and from the dirty thoughts dancing around his head of how exactly he would get this monster dick up his ass. Perhaps only part? Or could Bill manipulate that like he could the rest of his body, when he had his magic control back? Would Bill just shrink to something smaller, maybe ten feet with a one foot dick? Given its tentacular nature and taper, that should be doable, right?

 

Either way, capable later or not, he stood up and cleared his throat, asking in a huskier voice than expected if Bill would care to roll over onto his back. The idea made Bill chuckle, and he again grabbed the young man in one of his odd hindclaws, and, rolling that segment of his body over, deposited Dipper on top of the pad of flesh directly in front of his dick. With his eyes not utterly fixated on the neon tool writhing in anticipation before him, he could see why Bill hadn’t just stuck him in the cleft of the Y; a hole, sized to fit the dick, and covered in tiny tentacles, was apparently what Bill had drawn this from, and while certainly it would feel amazing to be caressed by all of them at once, he wouldn’t really have much use of his body, which is what he figured he’d need at the moment. He didn’t exactly want to get Bill’s insides all dirty, so he kicked off his shoes and socks, and kept his feet away as he rose to his knees and tried to wriggle out of his pants and boxers. Bill watched him, and smiled, which made him blush (as it always did), that briefest of concerns about what if Bill finds my fat gross washed away as he clamped his shapely thighs around the organ in front of him and Bill purred, purred and purred like he was trying to become a Sybian for his Dipper, and once his purring had subsided a little he rumbled something about beauty or Rubens.

 

Frankly, Dipper wasn’t listening, the act of simultaneously frotting Bill across most of his body and then getting vibrated on top of it while still (absolutely not) imagining trying to fit something like this inside, remembering all the things he’d seen when a curious teen on the internet… Well, it was a little too much for him to focus on much for about ten seconds. He had no clue, really, what else to do, with Bill so huge, and not really knowing if Bill had actual control over this, so he wrapped his arms around the tentacle-cock, waiting for it to stop wriggling so much. When that didn’t happen, he squished his chest on it, and his belly, and scooted closer, holding on. The fleshy blue under him, freed from its position under his feet, rose like it desired to clamp against whatever Bill’s body perceived itself to be mating with, and upon meeting Dipper’s ass and sac, stayed firmly put and wrapped itself around every little contour, trying to seal him against the demon body, ensuring Bill would get to mate the object of his affections. Dipper moaned at the sensation of the tiny tongues rubbing all over his inner thighs, his soft ass and the little hole Bill loved to take so much time playing with. Each of them moved independently, but wriggled away any bubble of air or excess liquid, and soon indeed the ones furthest from the edges- the ones teasing everything between his legs- felt like they had some suction to them. He could only imagine what it would be like if they were actually used, all three of them, for their purpose, whether that was (as he had guessed) to hold, or as some kind of extra stimulant. The thought, however, of Bill being sized right, and gripping him with them, making him powerless to move until Bill wanted him to, made his cock twitch against the much larger tentacle pushing back against him, and he opened his mouth to give Bill the first of many moans for this particular show.

 

As Dipper’s mouth opened, the tip of Bill’s tentadick, previously slathering a slightly iridescent liquid over Dipper’s slightly fluffy chest and drawing nonsense on his throat, shot up like it knew a hole had opened for it, and pushed into Dipper’s mouth, resting on his tongue until he breathed in, before moving in deeper. The human accepted the tip into his mouth, and pushed his head down a little, finding it easy to take as it was so nicely tapered as to only be the thickness of a nickel at the very tip. Bill certainly seemed to enjoy the addition of a mouth, and his hips rolled up, causing a ripple through his tail, which lashed with enough force to rip a small shrub it coiled around up and out of the ground by the roots, flinging it off into the forest. Dipper paused to glare at Bill for that, managing only brief irritation before the cobalt pushed him forwards and further against the long tentacle before him. He locked his legs behind the cover, and moaned again as the tongues started to take a decisive route, now stuck to him, and moved individually, each discovering a sensitive spot or a wiggle that particularly made him squirm before beginning to do so all at once. The ones teasing his ring pressed and pushed, trying to move their small selves inside, while the ones at his balls moved in gentle kneading motions, and thighs trailed in waves up and down. As they moved, the cobalt flesh moved with him, and his own eager thrust-not-thrusts as he bounced, up and down, moving to stimulate as much of his lover’s body as he could reasonably reach as well as satisfy the growing heat in his own gut.

Bill’s tentacle started to move on its own now, more concerted than the eager wiggling of before, as he shifted to curl around Dipper and provide him someplace to rest himself so he wasn’t hanging on and bouncing like a freakish carnival ride. It contracted and expanded, moving up and down his body, and now laid softly on his lover when it wasn’t pressing in waves. Dipper instinctively moved to grab nonexistent sheets, and Bill laughed a little as Dipper took instead a fold of soft skin in his hand- not at Dipper, but simply that he was making his boy feel this nice with only some simple grinding. It was smooth and rhythmic, and the demon appreciated Dipper’s attempt to stroke him still, though he knew Dipper liked to have something to grab and his tentacle wasn’t exactly grabbable. He used his secondary arms to prop himself up on either side, and ignored the groaning tree as he laid back against it, moving long fingers to the other side of his tentadick, smiling as Dipper took hold and used it like a hold bar, grasping at him gladly and bouncing on the tongues and against the long, heated thing he still tried to keep both his arms and legs around. He kept suckling a sweetish pre from the tip as he moved, though at times he needed a break to rest his legs and breathe, and then the tentacle moved to cup his cheek almost tenderly.

 

It didn’t take long before, between the pulses and Bill’s odd body mechanisms, the purrs that came in rounds punctuated by moans, and Dipper’s own efforts to use his whole body to rub off Bill, that the demon moaned out a warning to his little human mate, globs of pre speckling with darker shimmers. Dipper, lost in sensuality, in the oil making his skin tingle, coating throat and front and hinds, in having this odd strong writhing rubbing his cock between belly and muscle, and in hundreds of little motions designed to make him lose his mind, just looked up at his lover with hazy doe-eyes and made a questioning sound with Bill’s dick in the back of his throat.

 

Bill’s body coiled in at the sight alone, and the great demon’s possessive growling let into a bestial roar, hips jerking up once to slam an imaginary (or, rather, much larger) partner, bouncing Dipper and making him land hard on the cobalt pad, little tongues going haywire, sending him into shockwaves of pleasure- and Dipper did wonder for about half a second what the fuck had just happened before a pulse of heat between his thighs, arms, chest, lips made his eyes widen. Too late he realized he should have pulled away, there was no way he would be able to swallow all of what Bill would produce--! And then hot fluid was gushing down his throat, stuffing him within the first jet, and he pulled back as the second rushed over the roof of his mouth and face,dripping down in dark, gooey rivulets to sandwich itself between cock and body. He felt so full, almost uncomfortable from the sheer quantity, and some sort of tingling set in over his whole body, every place the third jet coated him in. It dripped down both of their cocks, fourth shot getting in his hair and down his back, fifth pulse a final overflow that coated the remainder of his plush form in space, set his nerves aflame in the most lovely of ways, and he came, hard. He was vaguely aware of bliss overwhelming him as the tentacle slid back in his mouth again, and of reflexive swallowing, so much left to milk from his lover, of eyes clouded by galaxies and tingles, of fullness that made his body tremble as the almost-fizzy sensation spread through him and washed him away with each popping bubble.

 

When he returned to his senses, and looked down, about half of him was smeared in what looked like liquid galaxy, and everything tasted like punch pop rocks and smelled like cinnamon. Bill was spread over the ground on his back, still panting, tentacle cock writhing and shaking off most of the cum before sliding into its odd sheath again. The little flaps shut, closing away access, and left Dipper stuffed full of thick goo. He attempted to stand, and some leaked out of his little hole, so much he was full of. Bill tenderly moved him with his first hands, down to the ground, and licked first himself clean of cum, then Dipper, tongue washing it off his swollen body with only the softest of licks. Then, with a questioning churr and a nod from his mate, Bill carefully pulled apart his cheeks to help him drain out some of the cum overflow, so he might not hurt so bad, if at all. Dipper shivered, and let Bill manhandle him, still too full to care, and drowsy from the sensations. Bill smiled down at Dipper once his eyes shut and he drifted off to sleep, and raised his precious human to the attic window, placing a towel under the human’s rear to hopefully soak up what would inevitably drip out. He pulled away the cumstained shirt and set it in the basket Dipper kept telling him to put clothes in before, and snuggled the little human into bed. He leaned against the shack, then, too, enjoying the remnants of cloves dissolving into cinnamon, and with three fingers wrapped tightly by his lover’s arms, he, too, napped. Dipper had done so well with that today. Once he was back to his usual, perhaps he’d take Dipper to learn about the other parts he hadn’t even touched. But for now, he had peace, and a delicate little human to share it with.


	2. Get Yourself A Lady

**Summary for the Chapter:**

> Dipper continues to explore new alien frontiers, this time investigating a peculiar cobalt crater... Who am I kidding, Dipper bones a monster Bill in the monster puss. Slog through the Connecting Story for the good stuff at the end.

Of course, when Dipper woke up, it was a little less peaceful. Bill attempted ignoring the muttered are-you-serious and what-was-I-thinking sentiments coming from his little mate, as he waddled around on his two chubby legs, and tried to figure a way to clean his mess but also put on pants. There were towel-on-wood sounds, and occasional wet drips, and soft padding feet that he knew by the gait and weight were his little lover’s. He couldn’t see through walls, but it was idea enough to guess Dipper’s plight. Last time he’d offered aid, Dipper, in all his adorable pride, had chosen to reject it, so this time he offered nothing and enjoyed the sunshine beating down on him. Eventually, though, and not to the demon’s surprise, he soon enough heard soft lips let out a plea, and he withdrew his hand from the window.

“Yes, dear?” He purred, the second word rising just a little too high for a question without humour as he turned his head to look through the open window. “Is my little bird too wet?”

Dipper shot Bill a stink-eye, and threw the cum-soaked and slightly dried towel at Bill, smacking his lover’s flat nose with the fabric. “Yes, actually, I am! How the hell am I supposed to clean up anything if I just make a mess wherever I go?” Bill’s main tongues flicked up to his nose and dragged the soggy towel into his mouth. He chewed on it like bubblegum before shrugging, and swallowing, which just made Dipper groan in annoyance. “You’re worse than the goat.”

The demon pressed his nose against the windowsill, the thin slits on either side flaring as it twitched up and down like a rabbit’s. “Am I really? How would you know what the goat is like?” He said, mock-possessively, as if somehow the statement had bothered him. Dipper waddled over, and when he reached to pat Bill, the demon flicked a tongue through quickly and licked his hand. A second, and much louder, exasperated noise left the human, and he wiped the drool off onto Bill as the demon laughed.

“Bill, not cool. Seriously, my room is a mess and I ran out of towels. The least you could do is not lick me,” he huffed, and wished the tiny galaxies following him would go away already. “Is this gonna clog the shower? Because if it’s not, you’re getting me a towel and I’m going to wash as you clean this all up.”

Bill shook his head. “I’ll be back soon,” he sighed, and wandered off to the cabin he’d been staying at when he was human. Once back with towels he batted into fluffy cleanliness, he gave one to the human, who wrapped it around his bulging waist and left, and the other to his puppet tail. The hatted triangle grabbed one with a weak, sticklike hand as he concentrated, and, threading the tail through the window, he mopped up after his chubby Dipper, all the way to the tile of the bathroom and the shut door. He washed the towel after, and set it to dry on the weather vane, and laid down outside and peeked through one of the lower windows. “Soos?” He asked, peeking in. “Soos. Hey Soos. You’re gonna need more towels. I ate them.”

~~~~

A few days had passed, with Bill mostly either napping, eating, or practicing his magic, trying to conjure or shift and force the boundaries and protocol back to the way they were before, before he’d been scrambled and shattered by the mindwipe gun. He was mainly focusing on the magic that altered himself, given how much of a hassle it was being incorrectly scaled for Earth sapients, and because it would be much easier to snatch a hoard of towels if he didn’t break the store being inside. By first identifying the “pieces of himself” (for lack of a better description) that were most connected to the old sources, and correctly ordering those fragmented sustaining pathways, he should be able to hold constant illusory magics like he did before, and actual physical affectations too. How many times had he tried this? He wondered briefly, as he repeated the actions for a sizeshift and examined one tiny shard of his fragmented spell-room in the mindscape. He sighed and picked up another when it didn’t work. Only about three trillion more to go. There were, of course, some that were easier to figure out than others; the little figurine of himself, for instance, had only been broken into about a hundred pieces, and putting that back together had been no problem, and neither had been using a vegetable as a human vessel until he could find whatever his body looked like. This aspect of his existence, too, hadn’t been too horribly wrecked, so he had been able to consume the human body to make this instead; but this, a complicated statuette that was his imagining of changing sizes? Of all the piles of broken things he’d sorted into possibility, this one was the most valuable to him right now. He’d re-knitted Dipper’s little sock puppet, and looked to it- or rather, its representation in his head- and patted its yarn hair. Soon, little human. A glove of a different purpose.

~~~~

Dipper, however, had a much easier solution for the issue of changing size. He gave his colossal monster boyfriend a wave goodbye as he hiked off into the forest, and came back a matter of hours later with a cyan-and-magenta crystal he dared not put in the light directly to look at. He fixed it to one of the outside spotlights with some clear tape and fishing line, and dragged the big monster by a tuft of filamentous not-hair to its range.

“Alright, now. You just curl up right there,” he said, quickly scooting out of the way of the spotlight.

“What’re you going to do with me?” Came a suspicious response, one Dipper shot a quirked eyebrow and a “really” at him for. “What? Can’t blame me entirely.”

“I suppose not. It’ll make you a more manageable size, so you can actually fit in the house and not devour the whole forest.” Dipper stepped back, and checked that Bill was within the staked-out string circle. Bill looked up at the crystal, ink eyes reflecting its shine. “Ready? Stay still now!”

The light flicked on, and a vibrant pink washed over the monster boyfriend, ever the colour of gravewax, almost making him look as though his blood wasn’t periwinkle and pale. And, quickly, the great lump began to shrink, shrink, forty feet down to thirty, twenty, finally ten. Dipper excitedly shut the lamp off and ran over to his slightly dazzled boyfriend, who was no longer used to changing sizes, and gave him a warm, soft hug.

A pair of twiggy fore-arms wound round the monstrosity’s human, and a smaller, but still strangely palmetto-leafed minor tongue, flicked out to lick and appreciate Dipper. “I feel very small and rather vulnerable,” he voiced, pulling away to curl his tail around and find nothing to hinder it. “I don’t like it. How long are you going to have me like this?”

“Well, until you can change yourself I guess. You were eating all the wildlife and making a mess of everything.” Dipper shrugged a little, but soon had grabbed a skinny hamsa-hand and was pulling Bill inside, giving an excited yell of “Soos! Look it worked!” as they entered.

~~~~~~~

Bill regretted everything. E-V-E-R-Y-T-H-I-N-G. Ever since he’d come inside, the small children had wanted to pester him incessantly, he’d not been allowed to hiss at them, nobody was scared of him, and he’d needed to resort to hiding upstairs so he wouldn’t get poked and prodded like some kind of “robot science experiment”, as one person put it. He refused to come downstairs for dinner, and Dipper had to bring it up in a little bowl and sit until he finally ate something.

The second day was less bad, since he just stayed upstairs and slept and ate all day, but it left him restless. Sure being lazy was nice, but there was nothing interesting inside. He’d rather go back outside and be forty feet long and have people gawk like he was some ridiculous animatronic than sit in an enclosure or behind tape.

The third day he was properly restless, solving jigsaws and making lego things only to smash them, and when the shop finally closed he relished the chance to play “tag” with the kids, so long as he was the one allowed to chase. Of course, the youngest of Soos and Melody’s three started to cry when he shot his tongue out at them and smacked the whelp hard on the back, and that was the end of that. Luckily, the effort worked off some of that excess energy and managed to actually sleep well enough.

Four, five, six days, finally a week passed. He’d taken to catching small animals, hares and doves and frogs, and tormenting and eating them when he got bored. It was a little harder, since he was smaller, and couldn’t strike them from a hundred and twenty feet away.

Eight days in, and after dinner Dipper thanked Melody and Soos, helped entertain the kids with stories for a bit, and then went upstairs to lay in bed and read.

Bill curled happily around Dipper best he could, something between a body pillow and a big spoon, and wrapped his tail around the arm Dipper used to turn pages. It gave him a sense of how long Dipper was taking to slog through whatever trash fantasy book he was currently engrossed in, and thereby how tired he was. This time, though, Bill noticed Dipper’s page-reading slowing down, but his heart rate speeding up. Confused, he raised a long stork’s neck and peered over at the page, only to have Dipper startle and shut it in a hurry. “Bill!” He quickly yelped, turning to look at the demon with a bit of shame in his tone. A shame that made one of the small fluffs mocking eyebrows raise a little.

“What are you reading that I can’t read too?” He asked, quirking his head a little, especially as the blush that rose up over Dipper’s cheeks told him exactly what it was.

“Nothing! You just surprised me! You don’t generally move. Now I’ve lost my page!” Quickly, he thumbed back through the pages, only to have a spare arm pluck the book away and scamper off the bed. Taller by a good deal, Bill sat up on his hindlegs and began to read the pages with clear laughter in his voice.

“‘Slowly, Ivy Moon shed her outergarments, the long obsidian cloak and tight leather corset that held in her bouncing, full breasts, perky with nipples hardened, rock hard. Off came the tight leather pants and high-heeled, leather boots, all as black as the still night around them, to reveal lingerie as white as her marble skin.’” A wide grin split his face, and as Dipper began to hop up and down while grabbing at the paperback’s pages, he only stretched higher and read louder.

“Oooh, here’s the good bits... ‘And slowly, he slid into her velvet womanhood, his turgid rod filling her up better than any inn meal.’ What kind of trash is this? That’s not even sexy. Who uses turgid?” He laughed, before looking down to see Dipper had gone from hopping up and down in anger to a sort of… Betrayed? Look, with tears welling up in his eyes. Well- he’d not been expecting that. Quickly, he settled back to ground level, and gave Dipper back his book. “What- Why are you crying? Hey- Don’t give me that look, this stuff is trash. I wasn’t making fun of you,” came the hurried excuses, and Dipper just snatched the book away and held it close.

“You can’t just take things like that!” He exclaimed, smacking Bill on the nose with the paperback. Bill jerked back, wriggling his rabbit-nose, rubbing the sting away. “Just because some of it is trashy doesn’t mean I don’t like other parts of it too! And you should know most books like this have at least one scene kinda like that, it’s supposed to make it mature. Which you aren’t right now.” Huffy, sure, but Bill sniffed a little at Dipper with his stinging nose and found a familiar scent lingering around the soft flannel pajama bottoms. Oh… Well that would explain the anger at interruption.

“I didn’t think you actually LIKED it,” he began, and received another smack.

Dipper placed the bookmark in, and marched to bed, turning off the light without a good night.

Bill picked up the book and began to read, confused about what had Dipper’s boxers in a wad, or more accurately, a wad in Dipper’s boxers. What was in there that he could possibly be so thrilled over? There wasn’t anything he couldn’t have in there! A handsome-ish man-- er, well, monster now but he’d fix that soon enough-- some tail, adventure, magic, friends… But he’d figure out what Dipper felt was missing, and fix it right up.

~~~~~~

Dipper watched Bill scurry up the stairs earlier than normal, and figured maybe he was tired from something. 

Bill regurgitated the pack of lingerie sealed in plastic he’d stolen from a store delivery truck the previous night and began to figure out how to put it on before Dipper went upstairs.

Dipper came upstairs in a couple more hours to find Bill was probably on something. There were wild flowers everywhere, some pretty like the daisies, and others utterly confusing, like the dandelions. A lit taper candle stood alone on the nightstand. And, on a well-made bed, laid his ten foot long monster boyfriend, in a double pair of black bras, one lacey, one satin, that contained nothing but pectoral muscle, tissue stuffing, and monster skin, and a very stretched and unhappy red lace boyshort panty covering the nethers that didn’t need covering. Bill perked up as he saw Dipper enter, and struck an attempt at a seductive pose, though with a tauric body stance it was rather difficult and just looked more awkward than sexy. He gripped a sprig of heavy pink-flowered foxglove in his teeth, and purred, quite literally.

Dipper shut the door on automatic reaction and stood where he was, just staring, until finally something came out of his mouth that mimicked the internal confusion at all of this.

“Bill… The fuck?”

The demon had been expecting praise, adoration, thanks, not a confused… Whatever this reaction was.

“What do you mean? I figured out what I needed to make up for!” The flowers dropped to the bed and he stretched out a leg, one of the y-flaps hiding his genitals unfurling to draw aside the red panties and heave a puff of cloves into the room. The other two splayed open, revealing neon insides. “So c’mere big boy and do what you’d like.~”

“Make- Make up for? What? You- You’re not talking about the book are you? Bill, I thought-”

“Nono, really! The only thing you don’t have there is a girl! So I’ll be the girl so you don’t feel like you need the book ones. You can skip those parts now.” He nodded sagely, and turned his ass to Dipper, lifting his tail and waving it side-to-side as seductively as he could manage through a panty.

“Are… You’re not jealous of the book, are you?” The clove-scent was drifting over to him now, and memories of the previous encounter drifted with it, making him blush and grow warmer than he’d like.

“No! Am not!” He shot back, though he was rather bad at lying in the monster-form as a blue blush formed under his jaw. It made Dipper grin, and then finally laugh.

“I can’t believe you’re jealous of books,” he said, finally understanding what the hell was going on, undressing with some slight clumsiness.

“No! I just- Don’t want you unsatisfied in our love life.” It was a poor recovery, and as Dipper scooted onto the bed, Bill was quick to change the subject and grabbed onto Dipper’s briefs. The scent of cloves was overpowering now, and Dipper tugged on the panties with the slightest of smirks, causing Bill to shiver happily. He’d been waiting for a while, and he’d definitely gotten more than a little damp. The monster shifted his weight back, and reached between his hindlegs, tugging away at the human’s underwear.

“Mm-hm. So, what was that about being a girl? Don’t you know you can’t just hop on?” Dipper teased, and pulled off his underwear, tossing them to the side.

Bill blinked in confusion. “What do you mean? I don’t need a condom or extra lubrication. I’m absolutely made to be hopped on.” He leaned forwards and wagged his hinds again, ears pricking back at the human who was faced with cobalt, pink, and lime. “So aren’t you going to get going?” There was a hint of excess eagerness in his voice, and the oily blues twitched and wriggled eagerly as they waited behind a thin red lace cover.

“Mmm… No.” Dipper slowly pulled down the red, lacy panties, pulled Bill back to be closer with his face as he sat back against the headboard. A surprised shift by Bill caused the overstrained panties to tear, and then snap entirely, and Dipper scooted the remaining parts down their respective limbs. “I think you can ditch the bras. They’re not all that cute without boobs to go in them.”

Bill did so glady, and craned his head back to look at what Dipper was doing as soon as his chests were free of them. He got just enough time to see Dipper lick his lips before there was warmth and heat and soft wetness against the blue hole. Automatically, Bill churred, and the fleshy flaps closed and tightened on his lover’s face. Dipper had to make some rather concerned sounds and push back on the not-very-filled-out ass and tail to make him let go. When he was finally freed from the cobalt flaps, he breathed hard and shook his head a little. “Bill- You can’t just- Smother someone like that okay- Don’t do that, alright? Not while my face is there.”

The blue blush under Bill’s throat darkened and spread. “Sorry. I didn’t mean to.”

Dipper went back with a little more caution this time, and traced his tongue over the clove-scented insides. Soon, the carnation and lime tentacle-dick had freed itself from its odd sheath, and was curled with the triangular flap massaging it, leaving two holes open for investigation.

Dipper guessed one’s dick wouldn’t go in a girl’s hole, in case it wasn’t clean when it went back and somehow you got… Yourself pregnant, so he focused on the one that was cobalt on the outside edge, but seemed more deep void black inside. Curiously, he stuck a finger inside, and found what felt like tight rings of muscle clamp down and squeeze tight around his finger, while the walls in-between undulated softly inwards, drawing in and trapping the finger. It took some effort to pull away, so he tried with two fingers, and began gently stroking and thrusting them in and out as best he could while looking to see what else Bill had. There was a bit of a pine-green tint towards the taint, but he couldn’t figure out why, and after the insistent pulling on his fingers had made them tingle with blood he had to pull them out. While Bill had mostly kept to purrs and breathy sounds with the fingers in, as Dipper pulled them away and curiously licked them, the sounds became insistent and then irritated when the fingers didn’t return.

Bill glared back at his human lover, about to snap a “Why’d you stop?,” before finding a face buried in monster snatch and any complaints drowned out with a happy moan. This was more like it. The feeling of a warm, wet, slippery thing sliding over his entrance made him sigh and arch back into Dipper’s lips, and Dipper was quite gladly and greedily lapping at the quite literally honey-flavored monster juices that were being squished out in rather plentiful quantities.

Inexperienced with this stuff as he was, Dipper mostly just licked and lapped, and occasionally suckled a little at, his monster boyfriend’s alien flower, not entirely sure what else to do with the foreign anatomy he’d only seen once before. Bill, after a bit of relaxing to his lover’s enthusiastic tonguing, began to rub and stroke away at Dipper’s cock, remembering to play nice and give his lover some pleasure too.

Finally, when Dipper felt both had enough of foreplay (seeing as Bill wasn’t giving many clues on that end), he pulled away his face and licked sticky lips, wiping his slightly pearlescent chin off with a hand before rising to his knees and adjusting their hips.

Bill was easy to move like this, eager to finally get a good pounding in, tail arching up over his back as Dipper moved to get in position. He watched with hungry ink-dot eyes as, almost too painfully slowly, Dipper rubbed his length over Bill’s open Y, smearing it in lustrous liquid, and finally, finally, pushed inside.

Bill let out a loud moan as Dipper made his way through five little internal rings, and immediately, his tail curled close around Dipper’s chest, and those opened folds suckered down around soft and chubby hips, keeping Dipper tightly close. It didn’t take much time before the undulating walls brought all seven of the little rings down around Dipper’s cock and began moving, fitting perfectly to his size, a slick and melting glove for the length given. He wasn’t even moving yet, and it felt like he was pumping along, each ring a different sensation of pleasure given to a different segment of him. A loud and pleased curse found its way out, and for a few moments, he had to just hold those bony hips and try not to be too loud as his human nerves screamed in amazed pleasure at this entirely inhuman pussy.

“Bill- Bill holy fuck loosen up I can’t move,” he half-moaned, half-begged, and reluctantly, the demon did. The flaps no longer suctioned so tight over each hip-bone and on that soft sac, and the rings no longer caught and clenched and squeezed as hard on Dipper’s cock, though he was still better than any toy or person Dipper had yet been with.

With moving now an option, Dipper wholeheartedly gave in to his own biology, and leaned forwards, starting to rock his hips. In and out, with wet slups and smacks sounding from each pull and push, Dipper found himself focused solely on that small meshing, the way each ring would cling and hold and only reluctantly give way to the pull-back, how what felt like thousands of tiny bumps melded to his cock and stroked over every atom, how the purrs and moans and curses sounded into the mattress would shake through the already stimulated nerves and vibrate what was, for all he cared, his whole being, straight from his cock to his brain. The more he shook his hips the more the tingling, heady clove-oil monster lube worked its way into his cock, balls, taint, and the longer he moved, the more that clove oil scent turned to spicy cinnamon and melted away any extra thoughts still left around after the initial shock from just pushing in.

It didn’t take very long for Dipper to feel that cinnamon heat pool below his navel, grow hotter thrust by thrust, until finally he was hammering in fast as he could go, trying to build this high up as far as it would go before he’d finally release. 

Dipper couldn’t tell how long it had been, but all too soon, that melting heaven clamped down hard, vicelike, as the tail and three soft flaps forced him close, hilted as far as he could possibly go, sealed in tight. Ripples travelled up his cock and Bill let out a loud snarl, followed immediately by a body-shaking rumble, and no amount of self-control could keep Dipper from cumming hard, grabbing onto Bill tight as his hands would clench, forehead pressed to sweaty back as tense after pulsing tense shot all he had into cobalt blue. The seven rings undulated and milked him for every drop, and for a while, all he saw was white, all he could feel was electricity, especially once this treatment didn’t stop for what felt like an eternity, but was no more than fifteen seconds or so. He didn’t even know if he was making sound, and when Bill’s grip on him finally loosened, jelly knees collapsed him to the mattress and left him exhausted and blank.

He came back to awareness some time after, moments or minutes or millennia, with his sticky, fading-cinnamon-scented lover coiled up tight against him. He felt warm and tingly, like he was drifting in warm ocean, warm sun. A gentle tongue drew over a cheek and he turned towards the familiar feeling with a soft sigh, before trying to grab and cuddle the equally tired bedmate.

The bigger demon purred, and curled himself to let his human be the big spoon for once. Bill regretted nothing.

**Notes for the Chapter:**

> Sorry it took so long for the second chapter, my muse drifted away. But, hopefully since it's wandered back for a while, I can get at least one more chapter out.

**Author's Note:**

> Tags will be added as chapters are added. Later chapters are kinkier.


End file.
